Improved calculation of the energy release in neutron-induced fission

Fission energy is one of the basic parameters needed in the calculation of antineutrino flux from nuclear reactors. Improving the precision of fission energy calculations is useful for current and future reactor neutrino experiments, which are aimed at more precise determinations of neutrino oscillation parameters. In this article, we give new values for fission energies of some common thermal reactor fuel isotopes, with improvements on three aspects. One improvement is more recent input data acquired from updated nuclear databases. The second improvement is a consideration of the production yields of fission fragments from both thermal and fast incident neutrons for each of the four main fuel isotopes. The third improvement is a more careful calculation of the average energy taken away by antineutrinos in thermal fission involving a comparison of antineutrino spectra from different models. The change in calculated antineutrino flux due to the new values of fission energy is about 0.32$%$, and the uncertainties of the new values are about 50$%$ smaller.